This invention concerns systems having media that have topographical features detectable by slider-mounted transducers sensitive primarily to a change in local aerodynamic boundary conditions.
To meet the insatiable demand for inexpensive and inexhaustible data storage, the long and steady march of progress in the field of data recording and electronic playback has relied on many technical approaches. No approach has outperformed the versatility and extremely high storage densities of magnetic recording, in which a signal is recorded by selectively varying the magnetic moments of physical regions of media such as flexible tapes or rigid (typically rotating) disks. Another broad class of approaches relies on variations in the physical shape of the surface of the media. Such features are not detected directly, but rather are used to cause corresponding variations in characteristics such as reflectivity, coercivity, and the like that may be detected accordingly (e.g., an optical detection system, in the case of variations in reflectivity).
One aspect of the invention is a data recording medium. The medium has machine readable topographical features and a hard coat layer (or stack) substantially conforming to the topographical features. The features affect a change in local aerodynamic boundary conditions between the recording medium and a slider-mounted non-magnetic transducer passing over the medium, which may be detectable by the transducer to playback the data encoded in the topographical features. The topographical features may be above or below the adjacent surface. The detectable change in local aerodynamic boundary conditions may affect temperature or pressure.